Figure 2. The impact of age (preterm (< 37 weeks) or term) and the CYP2D6 activity score (either 1, 2, or 3) on the plasma log M/M1 value. A lower M/M1 value hereby reflects a higher CYP2D6 activity, depending on both age and genetic polymorphisms. Individual plasma log M/M1 values were extracted from an earlier published dataset on tramadol disposition in neonates. There were no cases with a CYP2D6 activity score of 3 in the preterm age cohort. (M = tramadol; M1 = O-desmethyltramadol) (X-axis: preterm (< 37 week) or term (≥ 37 week) cases, Y-axis: plasma log M/M1 value) [49].
